In new building construction or in existing building construction where the wood joists or studs are completely exposed and readily accessible, providing additional structural support at the mounting site of a ceiling fan or a relatively heavy light fixture can be readily effected by well-known forms of brackets, bracing, etc. However, for a wall or ceiling mounting of a ceiling fan, relatively heavy light fixture, potted plant, etc. in existing building structures without ready access to the studs or joists, installation becomes considerably more difficult if removal of the wall or ceiling board is to be avoided.
Where the ceiling is between floors of a multi-story structure, installation can prove particularly troublesome. At the same time, the standard electrical box from which many fixtures are frequently hung cannot safely support more than about a 10 pound static load. However, units to be mounted such as ceiling fans for example, represent from about a 25 pound to about a 100 pound dynamic load such that a reasonably complex reinforcement of the electrical box has been utilized.
It has been common in order to achieve adequate support in the above situations to utilize a commercially available form of interjoist hanger assembly. The assembly is typically secured transversely to the stud/joists behind the wallboard above the four inch box opening at the mounting site. Pursuant to the requirements of the National Electric Code 370-17, installation of supported items such as ceiling fans are not to be directly supported from the box ears. Therefore, typically utilized in combination with the hanger assembly dependently supported at the opening is a modified electrical outlet box reinforced to accommodate the load value sought to be supported.